Two-cycle engine with charge pump therein



June 18, 1968 R. JAMES 3,388,693

TWO-CYCLE ENGINE WITH CHARGE PUMP THEREIN Filed March 15, 1967 5 Sheets-Sheet 1 INVENTOR RICHRD JAMES m ATTORNEYS R. JAMES June 18, 1968 TWO-CYCLE ENGINE WITH CHARGE PUMP THEREIN 3 Sheets-Sheet 2 Filed March 15, 1967 mvzm'o RICHA 11 JAMES s mm June 18, 1968 R. JAMES TWO-CYCLE ENGINE WITH CHARGE PUMP THEREIN 5 Sheets-Sheet 5 Filed March 15, 1967 United States Patent 3,388,693 TWO-CYCLE ENGINE WITH CHARGE PUMP THEREIN Richard James, 5025 Granville St., Vancouver, British Columbia, Canada Filed Mar. 15, 1967, Ser. No. 623,412 18 Claims. (Cl. 123-18) ABSTRACT OF THE DISCLOSURE The two-cycle engine has a cylinder therein for alternately pumping fuel charges into two power cylinders so that the base of the engine can be used for lubricating purposes only. Three cylinders curved about a common axis receive three pistons, a pump piston and two power pistons, which pistons are integrally united for oscillation about the axis. Ports or valves are provided for connecting the ends of the double acting scavenging pump cylinder to the two power cylinders.

BACKGROUND OF THE INVENTION This invention relates to a two-cycle engine having a charge pump therein for alternately directing fuel charges into each of two power cylinders thereof.

It is well known that two-cycle engines are very compact and efficient in operation. However, the big problem of the prior engines of this type is the one of providing lubrication for the various parts. In the commonly-used engine, the air-fuel mixture is directed into the base thereof which the piston is moving towards the top of the stroke. The pressure of the mixture in the base is increased as the piston moves towards the bottom of its stroke, at which time a port is opened to allow the mixture to flow into the cylinder ready to be compressed therein by the piston traveling towards the top of the stroke. This arrangement makes it impossible to maintain a body of oil in the base of the engine for lubricating purposes. As a result, oil has to be added to the air-fuel mixture in order to provide lubrication for the engine parts. The disadvantages of this system are well known.

The engine according to the present invention has a pair of power cylinders longitudinally curved about a common normal axis, and a pump cylinder longitudinally curved about the same axis. Power pistons are reciprocally mounted in the two power cylinders, and a pump piston is reciprocally mounted in the pump cylinder. Means is provided for constraining the three pistons to oscillate simultaneously in their respective cylinders about the common axis. The pump cylinder has port means through which fuel charges are directed alternately on opposite sides of the pump piston during reciprocation of the latter. Transfer means connects the pump cylinder to the power cylinders so that fuel charges are directed under the action of the pump piston alternately from the pump cylinder into the power cylinders. These power cylinders are provided with exhaust ports, and power take-off means is connected to the power pistons.

The power take-oft means preferably is a crank shaft rotatably mounted in a base of the engine, and a connecting rod connected to one of the power pistons. The pump and power pistons are preferably interconnected so that they oscillate as a unit. One of the advantages of this engine is that the base of the engine can contain oil for lubricating purposes, eliminating the necessity of adding oil to the engine fuel.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a reduced side elevation of an engine incorporating the present invention,

FIGURE 2 is a plan view of the engine of FIGURE 1,

3,388,693 Patented June 18, 1968 FIGURE 3 is a vertical section taken on the line 3-3 of FIGURE 2, showing the pistons at ends of their respective strokes,

FIGURE 4 is a view similar to FIGURE 3, showing the pistons half-way through their strokes,

FIGURE 5 is an enlarged perspective view of the unit formed by the pump piston and the two power pistons,

FIGURE 6 is a vertical section taken on the line 6-6 of FIGURE 3,

FIGURE 7 is a view similar to FIGURE 3, illustrating an alternative form of engine according to the invention,

FIGURE 8 is a fragmentary view illustrating a variation of the engine of FIGURE 7,

FIGURE 9 is a view similar to FIGURE 3 of yet another alternative form of the invention, and

FIGURE 10 is a section taken on the line 10-10 of FIGURE 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGURES 1 to 6 of the drawings, 10 is a two-cycle engine according to the present invention including a circular housing 12 made up of a peripheral wall 14 and two side walls 16 and 17 connected thereto, either one or both of which is removably connected to the peripheral wall in any convenient manner, such as by bolts 18. A base section 20 is provided at the bottom of housing 12 and opens into the latter at 21, see FIGURE 3. Actually, peripheral wall 14 continues around base 20, and side walls 16 and 17 cover said base. Circumferentially-spaced, arcuate inner cylinder walls 21 and 22 are mounted in housing 12 centrally thereof, and are concentric with the circular portion of peripheral wall 14 of said housing around a central longitudinal axis 23 thereof.

A pair of circumferentially-spaced, radial cylinder heads 24 and 25 extend between peripheral wall 14 and inner cylinder walls 21 and 22, respectively, and are connected to said walls. The heads may be fitted to said walls as shown, or they may be integrally formed therewith and with one of the side walls 16 or 17, if said one side wall is integrally connected to peripheral wall 14. In any case, heads 24 and 25 extend between and engage side walls 16 and 17. These heads form therebetween a pump cylinder 29, and the portions of housing 12 on the opposite sides of said heads 24 and 25 between peripheral wall 14 and cylinder walls 21 and 22 constitute power cylinders 31 and 32. Actually, the pump and power cylinders constitute an elongated chamber curved about axis 23 and divided circumferentially by heads 24 and 25 into the pump and power cylinders.

Power pistons 35 and 36 are curved longitudinally and slidably fit in cylinders 31 and 32 and are mounted for oscillation therein, and a pump piston 38 fits and is mounted for oscillation in cylinder 29. Suitable means is provided for constraining these three pistons to oscillate simultaneously in their respective cylinders. In this example of the invention, a shaft 40 extends through housing 12 centrally thereof normal to the pistons therein. The longitudinal axis of this shaft coincides with axis 23 around which the pistons oscillate.

Shaft 40 can be rotatably mounted in side walls 16 and 17, but in this example, the shaft is fixed against rotation to these walls. A hub 42 is rotatably mounted on shaft 40 within housing 12, and piston 38 is fixedly secured to said hub and radiates therefrom. Pistons 35 and 36 are connected to each other by an arm 43 which extends therebetween, and a connector 44 extends between and is connected to said arm and hub 42. Connector 44 extends upwardly through a gap 45 between cylinder Walls 21 and 22. Thus, the hub and three pistons are formed in a unit, as shown in FIGURE 5. Hub 42 rotatably fits within arcuate walls 21 and 22, while piston 38 projects outwardly from the hub through a gap 46 between said arcuate walls. Walls 21 and 22 form the inner walls of cylinders 31 and 32, while peripheral wall 14 forms the outer walls thereof. Side walls or covers 16 and 17 bear against the side edges of heads 24 and 25, the ends of hub 42, and the side edges of the three pistons, and constitute the side walls of the three cylinders. Suitable sealing rings and strips, not shown, are provided to seal the pump and power cylinders from each other. As these sealing rings and strips are well known in the art, they do not need description herein.

An intake port 47 is provided for pump cylinder 29. This port is preferably midway between heads 24 and 25 and in peripheral wall 14. However, the intake port could be provided in either of the walls 16 or 17, and it would be possible to provide two intake ports, one on each side of vertical centre line 49 which extends through axis 23 which is common to the three pistons. However, it is preferable to employ a single intake port 47 on the vertical centre line as shown. An air-fuel mixture is directed to port 47 in any convenient manner, not shown.

Although not absolutely necessary, it is preferable to provide pump piston 38 with an arcuate head 50 on its outer end which is curved to fit against the inner surface of peripheral wall 14, said head sliding along said inner surface when the pump piston oscillates in its cylinder. Head 50 is of such length in the circumferential direction that it uncovers port 47 when piston 38 is near either of the cylinder heads 24 or 25. Shortly after the pump piston starts to move away from each cylinder head, piston head 50 covers port 47.

When port 47 is uncovered, a charge of fuel is directed into pump cylinder 29, and as piston 38 approaches each of the cylinder heads, the charge is compressed in the cylinder. Suitable means is provided for directing the charges compressed by the pump piston into power cylinders 31 and 32, respectively. This can be done in a number of ways. One preferred way is illustrated in engine 10.

Cylinder 29 is provided with one or more ports 52 in side wall 17 adjacent cylinder head 24. A transfer duct 53 mounted on the outer surface of wall 17 extends from these ports to one or more ports 55 in power cylinder 31 spaced away from said head 24. Similarly, ports 57 are provided in cylinder 29 adjacent cylinder head 25, and these ports are connected by .a transfer duct 58 to corresponding ports 59 in power cylinder 32 spaced away from said head 25. Inlet or transfer ports 55 of cylinder 31 are covered by the side of piston 35 during most of the stroke of the latter, but when the piston approaches the end of its stroke away from head 24 it uncovers these ports. Similarly, ports 59 of cylinder 32 are normally closed by piston 36, but when the latter nears the end of its stroke away from head 25, these ports are uncovered, as shown in FIGURE 3.

Power cylinders 31 and 32 are provided with exhaust ports 61 and 62 in peripheral wall 14 near instake ports 55 and 59, respectively. Ports 61 and 62 are closed by pistons 35 and 36 as pump piston 38 approaches cylinder heads 24 and 25, respectively, but the exhaust ports are uncovered when the power pistons near the outer ends of their strokes away from the cylinder heads. Pis' tons 35 and 36 have faces 65 and 66 opposed to cylinder heads 24 and 25, and faces 65 and 66 have relatively large grooves or depressions 68 and 69 therein which register with exhaust ports 61 and 62 when the respective power pistons are at the ends of their outer strokes, groove 69 being shown in registry with exhaust port 62 in FIGURE 3. If desired, cylinder heads 24 and 25 may be formed with large grooves or depressions 71 and 72 therein facing and opposed to piston grooves 68 and 69. When piston 35 is at the inner end of the stroke near head 24, grooves '68 and 71 form a firing chamber 74, see FIGURE 3. Similarly, when piston 36 is at the inner end of its stroke near head 25, grooves 69 and 72 form a firing chamber 75. The compressed fuel charges in firing chambers 74 and 75 are fired in any well known manner, and in this example, spark plugs 77 and 78 are provided in peripheral wall 14 for this purpose. The inner ends of spark lugs 77 and 78 are positioned in firing chambers 74 and 75, respectively.

Suitable power take-off means is provided for engine 10. Although the power could be taken off through central shaft 40, it is preferable to provide a crankshaft 80 in base section 20 of the engine. This shaft is journalled in suitable bearings provided in the engine, and its centre of rotation is preferably on vertical centre line 49, although it is not absolutely necessary to be so arranged, and is on the side of normal axis 23 remote from the pump piston of the engine. A connecting rod 82 extends between the crank shaft and one of the power pistons. In this example, connecting rod 82 has an end 83 connected to a crank of crankshaft '80, and an opposite end 84 mounted on a pin 85 which is connected to power piston 35. With this arrangement, the oscillation of power pistons 35 and 36 in their respective cylinders causes crankshaft 80 to rotate. The throw of the crankshaft and the length of connecting rod 82 are such that each of the power pistons is at the inner end of its stroke when it reaches a position near the head of its cylinder, piston 35 being shown in this position in FIGURE 3, and is at the end of its outer stroke uncovering the transfer ports of its cylinder and bringing the exhaust port of the cylinder into communication with the cylinder, piston 36 being shown in this position in FIGURE 3.

Engine 10 is cooled in any desired manner. Cooling fins 88 are provided for this purpose. If desired, peripheral wall 14, cylinder walls 21 and 22, cylinder heads 24 and 25, and end walls 16 and 17 can be made hollow in order that a cooling fluid can be circulated therethrough. The cooling of the engine is accomplished by means well known in the industry.

The operation of engine 10 is quite simple. With the pistons in the positions shown in FIGURE 3, there is a fuel charge compressed in firing chamber 74, and cylinder 29 between piston 38 and cylinder head 24 is filled with a fuel charge which has entered through intake port 47. When the charge in chamber 74 is fired, piston 35 is driven downwardly in its cylinder 31 through a power stroke. At the same time, pump piston 38 moves towards head 24, and when port 47 is closed by piston head 50, the fuel charge is compressed in cylinder 29. When power piston 35 reaches the outer end of its stroke, transfer ports 55 and exhaust port 61 are uncovered. The exhaust gases are discharged through the latter while the compressed charge in cylinder 29 flows through transfer duct 53 into cylinder 31, ready to be compressed when piston 35 moves back towards head 24.

Starting again with the pistons in the positions shown in FIGURE 3, it will be seen that cylinder 32 has just exhausted through port 62 and a charge of fuel has been directed into said cylinder under the action of pump piston 38 through duct 58 and transfer ports 59. Piston 36 is moved towards cylinder head 25 through a compression stroke while piston 35 is moving through its power stroke. The fuel in cylinder 32 is compressed into firing chamber 75, and at the same time, pump piston 38 moves towards head 24 so that when piston head 50 clears intake port 47, a new charge of fuel is directed into cylinder 29 between the pump piston and cylinder head 25.

With this arrangement, it is not necessary to direct fuel charges into base section 20 before they are directed into the power cylinders. As a consequence, a bath of oil may be maintained in base section 20 for lubricating the crankshaft, pistons and other elements, as is done in standard four-cycle engines. In addition, while the two power pistons are reciprocating in their respective cylinders, one is always on a power stroke and the other on a compression stroke. Pump piston 38 being connected to the power pistons through hub 42, there is no necessity for gears or other driving connections between these elements.

FIGURE 7 illustrates a two-cycle engine 100: is the same as engine 10 in all respects excepting the means for transferring the compressed fuel charges from pump cylinder 29 to the power cylinders 31 and 32. Transfer ports 52, 55, 57, and 59, as well as transfer ducts 53 and 58, are omitted from engine 10a. In place of these, cylinder head 24- is provided with a transfer port therein, :and a poppet valve 91 normally resting on a seat 92 formed in .the head, said valve opening towards power cylinder 31. The poppet valve has a stem 93 which slidably extends through a guide 94 and into pump cylinder 29. A light spring 95 on this stern tends to keep valve 91 on its seat 92. If desired, a disc 96 may be provided on the end of stem 93 within cylinder 29 positioned so as to be touched by pump piston 38 when the latter reaches the end of its stroke when moving towards head 24. This disc, if used, acts as part of stem 93.

Similarly, cylinder head 25 is provided with .a transfer 3 port 100 therein controlled by a poppet valve 102 which opens towards power cylinder 32. The remaining elements associated with valve 102 are the same as those associated with valve 91.

Assuming that power piston 36 is at the inner end of its stroke near cylinder head 25, as shown in FIGURE 7, the compressed charge in cylinder 32 is fired. The pressure within this cylinder keeps valve 102 closed while pump piston 38 moves towards head 25. As pistons 36 and 38 near .the ends of their strokes, exhaust port 62 is opened, relieving the pressure in cylinder 32, at which time, the pressure of .the fuel charge in cylinder 29 between piston 38 and head 75 causes valve 102 to open to allow the charge to flow into cylinder 32. The entrance of this charge flowing longitudinally of the power cylinder helps to exhaust the latter through port 62. Although it is not really necessary, the stem of valve 102 can be engaged by pump piston 38 when the latter nears the end of its pressure stroke, thereby ensuring that valve 102 opens. When piston 36 starts on its compression stroke, the pressure in cylinder 32 starts .to increase, and as pump piston 38 is moving away from head 25, the pressure between this piston and the head begins to drop, so that valve 102 returns to its seat to close port 100.

Valve 91 operates in the same manner as valve 102 to permit a fuel charge to be directed into cylinder 31 as piston 35 nears the end of its power stroke and pump piston 38 approaches cylinder head 24.

FIGURE 8 illustrates an engine 10b which is very similar to engine 10a. In engine 10b, valve 91 is positively operated so that it will open and close exactly when required. In this case, spring 95 is strong enough to keep the valve closed regardless of the pressures on opposite sides of cylinder head 24. A shaft 107 extends transversely of pump cylinder 29 adjacent head 24, and is journalled in the side walls 16 and 17 "of the engine. A cam 108 is mounted on this shaft and bears against the end of valve stem 93, so that when the cam rotates, it alternately opens valve 91 and allows spring 95 to close it.

Shaft 107 is rotated in any convenient manner. In this example, a sprocket 110 is mounted on the shaft outside chamber 29, and is connected by a chain 111 to another sprocket 112 mounted on the portion of crankshaft 80 that extends out of base 20.

Cam 108 is rotated and is designed to open valve 91 as power piston 31 approaches the outer end of its power stroke, and it permits the valve to close just as the piston closes exhaust port 61.

It will be understood that valve 102 is cam operated in exactly the same manner as valve 91.

Another modification of this invention is illustrated in FIGURES 9 and 10. Engine 10c is similar to engine 10, but it has a different transfer port arrangement. In this example, transfer duct 53, and transfer ports 52 and 55 have been omitted. A pair of arcua-te port plates and 121 extend through cylinders 31, 29 and 32 along the inner surfaces of side walls 16 and 17. Plates 120 and 121 are secured at their opposite ends to power pistons 35 land 36, and slidably extend past the edges of cylinder heads 24 and 25. In this case, these heads preferably are removably mounted in the concentric cylinder walls 14, 21 and 22. These plates extend radially between said walls 14, 21 and 22, and they oscillate back and forth with the two power pistons.

Plate 120 has one or more elongated ports 125 therein on one side of pump piston 38, and another set of one or more elongated transfer ports 127 formed therein on the opposite side of said pump piston. Transfer ports 125 are so located that as power piston 35 approaches the end of its power stroke, these ports overlap the edge of head 24 and open into both of the cylinders 29 and 31. This enables fuel to transfer from the pump cylinder to the power cylinder at this time. The thickness of plate 120 may be such that these ports therein are sufficient to transfer the required amount of fuel between the cylinders. The ends of each elongated port 125 constitute transfer ports in the pump and power cylinders interconnected by the portion of said port 125 extending past cylinder head 24. However, if desired, one or more elongated ports 129 may be formed in side wall 16 across the edge of head 24 so that ports 125 move into registry therewith as they approach the cylinder head. In this case, a transfer duct 130 is mounted on the outer surface of side wall 16 over ports 129.

When power piston 36 approaches the end of its power stroke, transfer ports 127 move past the edge of cylinder head 25. If desired, one or more ports 133 may be provided in wall 16 across the adjacent edge of cylinder head 25. In this case, another transfer duct 134 would be mounted on the outside of wall 16 over said ports 133.

An important advantage of engine 100 is that when the transfer ports start to bring pump cylinder 29 into communication with one of the power cylinders, for example, cylinder 31, exhaust port 61 is just opening so that the fuel charge entering the power cylinder by way of the transfer ports helps to scavenge that cylinder, and the movement of the gases in the cylinder is from the head end thereof straight towards the piston which is at the end of its power stroke. M

It will be understood that if desired, the same transfer port arrangement may be provided in port plate 121 and side wall 17, although these have not been shown in the drawings. If desired, plate 121 can be omitted altogether. Although transfer ports and transfer ducts have been shown on one side only of the pump and power cylinders of engine 10, it will be understood that there may be a similar transfer port arrangement on the opposite side f said cylinders.

I claim:

1. A two-cycle engine comprising a pair of power cylinders longitudinally curved about a common normal axis, a pump cylinder longitudinally curved about said axis, power pistons mounted in the two power cylinders for oscillation therein, a pump piston mounted for oscillation in the pump cylinder, means constraining said three pistons to oscillate simultaneously in their respective cylinders about said axis, port means for directing fuel charges into the pump cylinder alternately on opposite sides of the pump piston, transfer means for directing said fuel charges under action of the pump piston alternately from the pump cylinder into the power cylinders, exhaust ports in the power cylinders, and power take-off means connected to the power pistons.

2. A two-cycle engine as claimed in claim 1 including means rigidly connecting the three pistons together.

3. A two-cycle engine as claimed in claim 1 in which the pump piston extends radially away from said common axis, and the power pistons are spaced from said pump piston on opposite sides thereof.

4. A two-cycle engine as claimed in claim 2 in which said power take-off means comprises a crankshaft, and a connecting rod connected at one end to the crankshaft and at the opposite end to one of the power pistons.

5. A two-cycle engine as claimed in claim 4 in which said crankshaft is spaced radially from the common axis in a direction away from the pump piston.

6. A two-cycle engine comprising an elongated chamber curved longitudinally about a central normal axis, circumferentially spaced cylinder heads in the chamber dividing the latter into a pump cylinder between two power cylinders, power pistons mounted for oscillation in the power cylinders and movement towards and away from said heads, a pump piston mounted for oscillation in the pump cylinder and movement between said heads, means constraining said three pistons simultaneously to oscillate in their respective cylinders about said axis, port means for directing fuel charges into the pump cylinder alternately on opposite sides of the pump piston, transfer means for directing said fuel charges under action of the pump piston alternately from the pump cylinder into the power cylinders, exhaust ports for the power cylinders, and power take-01f means connected to the power pistons.

7. A two-cycle engine as claimed in claim 6 in which the constraining means comprises a shaft positioned with the longitudinal axis thereof coinciding with said common axis, each of said three pistons being connected to said shaft and substantially radiating therefrom.

8. A two-cycle engine as claimed in claim 7 including means rigidly interconnecting the three pistons so that when one power piston is at the end of a stroke towards the head of its cylinder, the other power piston is at the end of a stroke away from the head of its cylinder, and the pump piston is near the latter head.

9. A two-cycle engine as claimed in claim 6 in which said port means comprises a port in a wall of the pump cylinder substantially midway between said cylinder heads.

10. A two-cycle engine as claimed in claim 6 in which said transfer means for each power cylinder comprises a first port in the pump cylinder near the head of said each power cylinder, a second port in said each power cylinder spaced from the last-mentioned head, and passage means interconnecting said first and second ports.

11. A two-cycle engine as claimed in claim '6 in which said transfer means for each power cylinder comprises a port in the head of said each cylinder, and a valve normally closing said port and movable towards said each power cylinder to uncover the port.

12. A two-cycle engine as claimed in claim 11 in which said valve is a poppet valve having a stem extending through the port into the pump cylinder far enough to be contacted by the pump piston as the latter approaches the end of a stroke towards the head of said each power cylinder to unseat the valve.

13. A two-cycle engine as claimed in claim 11 in which said valve is a poppet valve having a stem extending through the port into the pump cylinder, and including a light spring on said stern for normally retaining the valve in position closing said port.

14. A two-cycle engine as claimed in claim 11 in which said valve is a poppet valve having a stem extending through the port into the pump cylinder, and including a strong spring on said stern normally retaining the valve in position closing said port, and a driven cam for engaging the stem to open the valve when the piston in said each power cylinder is near the end of its power stroke.

15. A two-cycle engine as claimed in claim 6 in which said elongated chamber is incorporated in a casing having a base section on the side of said central axis remote from the pump piston, and said power take-01f means comprises a crankshaft rotatably mounted in the base section, and a connecting rod connected at one end to the crankshaft and at the opposite end to one of the power pistons.

16. A two-cycle engine as claimed in claim 6 in which said transfer means comprises an arcuate plate extending between and connected to the two power pistons in their respective cylinders, said plate extending along and completely covering a side wall of each power cylinder and slidably extending past edges of the heads of said power cylinders, and at least one transfer port in said plate on each side of the pump piston, each said one port being positioned to overlap the edge of a cylinder head when the pump piston is near the latter head to bring the pump cylinder into communication with the power cylinder on the opposite side of the last-mentioned cylinder head.

17. A two-cycle engine as claimed in claim 6 in which said transfer means comprises an arcuate plate extending between and connected to the two power pistons in their respective cylinders, said plate extending along and completely covering a side wall of each power cylinder and slidably extending past edges of the heads of said power cylinders, transfer port means in said plate adapted to bring the pump cylinder into communication with each power cylinder when the pump piston nears the head of said each power cylinder.

18. A two-cycle engine as claimed in claim 16 including ports in the wall of the pump cylinder and each power cylinder adjacent each cylinder head positioned to be overlapped by the transfer ports in the plate When said transfer ports overlap said each cylinder head, and a transfer duct extending between the wall ports adjacent each cylinder head.

References Cited UNITED STATES PATENTS WENDELL E. BURNS, Primary Examiner. 

